Iowa Population By County in 2020
Updated on June 16, 2025.
Based on the US Census Vintage data estimates, in 2020, the population of Iowa was 3,191,141. Among all Iowa counties, Polk had the highest population (493,039), followed by Linn (230,433), and Scott (174,617). Adams was the least populated county (3,710).
Hover over or click on the counties in the map below to see the populations. The data can also be found in a table below. You can use the table to sort, filter, and explore the data further.
You can see similar information for other states and by state for the United States.
Related Topics: Iowa Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage).
See this for other years:
Iowa Population By County in 2020
Iowa Population By County in 2020
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| County | Population | % of State Population |
|---|---|---|
| Adair | 7489 | 0.24 |
| Adams | 3710 | 0.12 |
| Allamakee | 14069 | 0.44 |
| Appanoose | 12283 | 0.39 |
| Audubon | 5680 | 0.18 |
| Benton | 25550 | 0.80 |
| Black Hawk | 131049 | 4.11 |
| Boone | 26702 | 0.84 |
| Bremer | 25007 | 0.78 |
| Buchanan | 20606 | 0.65 |
| Buena Vista | 20808 | 0.65 |
| Butler | 14334 | 0.45 |
| Calhoun | 9895 | 0.31 |
| Carroll | 20734 | 0.65 |
| Cass | 13115 | 0.41 |
| Cedar | 18483 | 0.58 |
| Cerro Gordo | 43021 | 1.35 |
| Cherokee | 11658 | 0.37 |
| Chickasaw | 11985 | 0.38 |
| Clarke | 9730 | 0.31 |
| Clay | 16337 | 0.51 |
| Clayton | 17034 | 0.53 |
| Clinton | 46432 | 1.46 |
| Crawford | 16492 | 0.52 |
| Dallas | 100544 | 3.15 |
| Davis | 9115 | 0.29 |
| Decatur | 7733 | 0.24 |
| Delaware | 17454 | 0.55 |
| Des Moines | 38856 | 1.22 |
| Dickinson | 17773 | 0.56 |
| Dubuque | 99310 | 3.11 |
| Emmet | 9342 | 0.29 |
| Fayette | 19448 | 0.61 |
| Floyd | 15593 | 0.49 |
| Franklin | 9995 | 0.31 |
| Fremont | 6567 | 0.21 |
| Greene | 8750 | 0.27 |
| Grundy | 12347 | 0.39 |
| Guthrie | 10619 | 0.33 |
| Hamilton | 15011 | 0.47 |
| Hancock | 10758 | 0.34 |
| Hardin | 16826 | 0.53 |
| Harrison | 14567 | 0.46 |
| Henry | 20447 | 0.64 |
| Howard | 9497 | 0.30 |
| Humboldt | 9597 | 0.30 |
| Ida | 7029 | 0.22 |
| Iowa | 16653 | 0.52 |
| Jackson | 19453 | 0.61 |
| Jasper | 37818 | 1.19 |
| Jefferson | 15699 | 0.49 |
| Johnson | 153052 | 4.80 |
| Jones | 20654 | 0.65 |
| Keokuk | 10012 | 0.31 |
| Kossuth | 14791 | 0.46 |
| Lee | 33529 | 1.05 |
| Linn | 230433 | 7.22 |
| Louisa | 10825 | 0.34 |
| Lucas | 8620 | 0.27 |
| Lyon | 11923 | 0.37 |
| Madison | 16628 | 0.52 |
| Mahaska | 22162 | 0.69 |
| Marion | 33414 | 1.05 |
| Marshall | 40091 | 1.26 |
| Mills | 14418 | 0.45 |
| Mitchell | 10586 | 0.33 |
| Monona | 8742 | 0.27 |
| Monroe | 7596 | 0.24 |
| Montgomery | 10330 | 0.32 |
| Muscatine | 43155 | 1.35 |
| O'Brien | 14149 | 0.44 |
| Osceola | 6200 | 0.19 |
| Page | 15200 | 0.48 |
| Palo Alto | 8993 | 0.28 |
| Plymouth | 25694 | 0.81 |
| Pocahontas | 7068 | 0.22 |
| Polk | 493039 | 15.45 |
| Pottawattamie | 93655 | 2.94 |
| Poweshiek | 18628 | 0.58 |
| Ringgold | 4643 | 0.14 |
| Sac | 9800 | 0.31 |
| Scott | 174617 | 5.47 |
| Shelby | 11727 | 0.37 |
| Sioux | 35897 | 1.13 |
| Story | 98651 | 3.09 |
| Tama | 17044 | 0.53 |
| Taylor | 5861 | 0.18 |
| Union | 12128 | 0.38 |
| Van Buren | 7218 | 0.23 |
| Wapello | 35327 | 1.11 |
| Warren | 52591 | 1.65 |
| Washington | 22541 | 0.71 |
| Wayne | 6502 | 0.20 |
| Webster | 36991 | 1.16 |
| Winnebago | 10656 | 0.33 |
| Winneshiek | 20051 | 0.63 |
| Woodbury | 105952 | 3.32 |
| Worth | 7430 | 0.23 |
| Wright | 12923 | 0.41 |